The FEIN 31333111000 Genuine Gearbox Housing is an original replacement housing for selected FEIN ASCD 18 W2 and ASCD 18 W4 cordless impact wrench/driver models. It houses and supports the internal gearbox components and is suitable for replacing a cracked, damaged or worn original housing. FEIN parts data identifies 31333111000 specifically as the gearbox housing for both compatible ASCD 18V machines.